Outer Limits 4x4 Board

G"Day all just trying to do the sums on a new set up, Basically I want to run 33"s I currently have a 1.3 with a 1 litre transfer, 3.7 diff Gears and 30" tyre's. Now I have purchased a set of 4.6 Vitara diff gears and I am looking at fitting 33' tyres my question is:

1.) Will this thing be a slug off the line?
2.) Will it be low enough for crawling up hills?
3.) What will my RPM be at 100kmh?
4.) Are 33's too big for this set up?

Here's my Gear Calculation Print out:



Here's the Gear Calculator if you want to play with some figures:

http://www.lepayne.com/gears.html

Your thoughts and advise appreciated greatly,

cheers in advance Robb.

1) it won't be a slug off the line.
2) yes it will
3) 3800-4000 depending on true tyre size
4) 33's are perfect for that setup

Thanks Joe, I should have just cleared that all up when I picked them up from you thanks again buddy!

I'm going to put my 2c worth in here, really only to illustrate that there's an alternative view.

Your car, set up the way you are planning, will be very well geared on road. Probably perfectly geared for a 1.3 litre car.

However, I don't think that 42:1 is enough crawl ratio, or more importantly, it's not enough crawl ratio for 33's.

The key is that when everyone calculates cruising speed, they take tyre size into account, but when they calculate crawl, everyone pretty much looks at the number alone.

Really, the important number is speed at idle in first gear figure.

For a stock sierra, that's 3.1km/h and for your planned setup, you get 2.6 km/h. That's not much different.

Now take into account traction. You're adding masses of traction. Traction adds more load on the engine. Rolling resistance also increases, moreso as you deflate your tyres.

The end result, in my opinion, is that 42:1 and 33's will feel like inadequate gearing, and you'll spend a lot of time going faster than you needed to considering the traction you had, just to keep the engine on song.

I'm going to suggest that to be really comfortable with 33's in steep technical terrain, you need about 50% more low range than you're planning - so, 60:1 or so- which is exactly what you'd get with 4.9 transfer case gears. These will make no difference to your (excellent) road gearing but run you to 66:1 crawl, and almost exactly 50% lower than stock gearing , taking tyre size into account.

In any case, the 4.6:1's are a great idea, it's all about the transfer.

Just some stuff to ponder.

Steve.

PS we have a car in the club that's running 35's an auto, and 42:1 crawl. I't's pretty tall geared in the bush. It's OK, but not ideal. Note that the auto effectively doubles 1st gear under load.

Thanks Gwagensteve that definately gives me something to think about! I think i'll do the diffs and tyres and see how she is first then i'll see about transfer gears once I've driven it in some of the terrain we usually drive and go from there. Cheers Robb.

BOGFROG wrote:Thanks Gwagensteve that definately gives me something to think about! I think i'll do the diffs and tyres and see how she is first then i'll see about transfer gears once I've driven it in some of the terrain we usually drive and go from there. Cheers Robb.

robb... you seem like a bloke that can 'drive'. your setup will be fine. in fact, you are welcome to drive any of our vehicles offroad with that same system (there are a few). plus, with the way you are heading you will have far less drivetrain headaches and issues.

joeblow wrote:

BOGFROG wrote:Thanks Gwagensteve that definately gives me something to think about! I think i'll do the diffs and tyres and see how she is first then i'll see about transfer gears once I've driven it in some of the terrain we usually drive and go from there. Cheers Robb.

robb... you seem like a bloke that can 'drive'. your setup will be fine. in fact, you are welcome to drive any of our vehicles offroad with that same system (there are a few). plus, with the way you are heading you will have far less drivetrain headaches and issues.

Cheers Joe, yeah not rushing into transfer gears, just want to see how she goes first! as long as I can spin up 33's I can deal with Low range if I find I need lower gearing we'll worry about that then but we'll see how she goes first! it's the old story Mod, Drive it and Mod more if needed? I will be saving up for air lockers after this mod anyway!

If you're currently open diffed or locked one end only then 42:1 is plenty. You'll need the momentum. Low geared cars with open diffs are terrible.

I vote the moment you are locked you'll be aching for more gears. You've done the right thing by gearing the car for road use with the tyres you plan on running. You now need to treat low range as a separate problem and the answer to that question will change as you add traction. it will also change depending on what you are driving. If you driver flatter tracks and more mud you need less gears. Steeper tracks/more rock= more gears.

Steve

PS Joe

There's nothing to be gained by turning this into a pi$$ing contest about good driving vs low gears. I've answered Bogfrog's questions by providing an alternative view.

Gwagensteve wrote:
PS Joe

There's nothing to be gained by turning this into a pi$$ing contest about good driving vs low gears. I've answered Bogfrog's questions by providing an alternative view.

for me

Thanks for Both your input much appreciated Robb.

lol this looks like it could turn into an episode of jerry springer at any moment =P

I like the idea of a lower low range though and as such would say tcase gears would be a better option purely for that reason alone. The difference between standard high and low range is pretty poor, and tcase gears negate that issue.

I disagree with Joe (respectfully). I was watching a youtube clip of a car that joe had built (4play) and geared via diff gears. The car is RPM's blue hardtop/bushwacker flares/SPOA and 33/34" combo. It was trying to do a simple step up but kept stalling, and had to give it plenty of berries to stop it dieing. This was pretty tricky as it was off camber and wheel placement was critical. a slower crawl ratio would have been perfect. I am kicking myself for loosing the vid and can't seem to find it. I run 33's, 3.9 diffs and 6.5 transfer and its perfect. I had 31's with 4.9's in my last set up and that was perfect. I wouldnt run 4.9's with 33's though.

^^^^ Refering to---->>>http://www.youtube.com/watch?v=GkTdt5lzivQ

Spike_Sierra wrote:I disagree with Joe (respectfully). I was watching a youtube clip of a car that joe had built (4play) and geared via diff gears. The car is RPM's blue hardtop/bushwacker flares/SPOA and 33/34" combo. It was trying to do a simple step up but kept stalling, and had to give it plenty of berries to stop it dieing. This was pretty tricky as it was off camber and wheel placement was critical. a slower crawl ratio would have been perfect. I am kicking myself for loosing the vid and can't seem to find it. I run 33's, 3.9 diffs and 6.5 transfer and its perfect. I had 31's with 4.9's in my last set up and that was perfect. I wouldnt run 4.9's with 33's though.

It probly just had a prick of a carby , and was flooding .

It's also still running a chain driven transfer case.
A roctoy ring won't fit it, so I believe he has got one custom made.

After all the work that went into this car it would have been a pretty minor job to put a 1.3 leafy case in with some gears to make the low range more useable.

Have spoken to the guy and he is not happy with the gearing.
As Steve was saying he does not have the ability to crawl in 1st/2nd gear as he would if he had either 4.6 with diff gearing or 6.5 with standard diff gearing.
It's a fact.


Cheers,
Paul

Spike_Sierra wrote:I disagree with Joe (respectfully). I was watching a youtube clip of a car that joe had built (4play) and geared via diff gears. The car is RPM's blue hardtop/bushwacker flares/SPOA and 33/34" combo. It was trying to do a simple step up but kept stalling, and had to give it plenty of berries to stop it dieing. This was pretty tricky as it was off camber and wheel placement was critical. a slower crawl ratio would have been perfect. I am kicking myself for loosing the vid and can't seem to find it. I run 33's, 3.9 diffs and 6.5 transfer and its perfect. I had 31's with 4.9's in my last set up and that was perfect. I wouldnt run 4.9's with 33's though.

Hey guys... that boghole was crazy... i thought i was going to lay it over for sure!
The reason why i kept stalling was that i havn't got much clutch travel anymore and i can't drive... bahaha.... but the gearing is generally really good... i never seem to have problems going up hills or anything... it's got 5.1 : 1 diff gears...

In Joes defence, he builds modded zooks that are fully engineered and road legal. Mine is engineered for 31's, but at the time of that vid, i was running 33 inch Simex's which are a BIG tyre (they measure 34 inches). The zook never felt right with those tyres (gearing and steering etc) I'm now running 33 inch Silverstones which are smaller in both width and diameter. I'm yet to test the extremes out as the zooks been off the road, with a few minor dramas which are now all fixed, but she drives heaps better on the road (i'm talking gearing wise). So she should go even better offroad now...





Yes, i do have a coily transfer case in the zook at the moment. Apparently it was in the zook before Joe starting working on it... I can't be bothered swapping it over, cos it seems to working fine... and i have had a Roktoy ring made up for it... So if you coily owners are after a roktoy ring get in touch with chris...

Dozoor wrote:It probly just had a prick of a carby , and was flooding ..

It's EFI...

Nice Jigger RPM,
I think the fear of laying it over and falling into that drop off was the major problem in that Vid I don't blame you but some times you just have to trust the people outside the car as they can see exactly what the car is doing or gonna do. I Don't think the gearing had anything to do with it plus the fact that you were in two holes, off camber and trying to climb on your right while a tree root caused havoc underneath you, but as said in your video comments Persistance Pays off! Good Work!

I've said it plenty. RPM's Zook is awesome. My zook is set up almost exactly te same as RPM's, Both built by Joe. I love mine. I run 34's with 5.12's and for me its enough gearing. I plan on joining the zook club very shortly which means I will get to see other zooks and see how lower geared ones work. However, for this thread I would recommend my 33-34" tyres and 5.12 diff gears.

Be ok in the mud but personally id drop it about 4" .

JMO.

Dozoor wrote:Be ok in the mud but personally id drop it about 4" .

JMO.

your spot on dozoor... It's awesome in mud, but scary on side angles...

I don't know why people are against tcase gearing over diffs, you will always find an instance when you wish you had lower gearing. That vid shows it, gearing would mean you could have let the clutch out fully allowing you to consentrate more on other things. I really think we need a comparison between the two in a head to head style situation as all we have here is two sides loving their current setup. We should try and organise this, would be great tech!

Have always loved your zook rpm, don't feel like I have anything against it

Dozoor wrote:Be ok in the mud but personally id drop it about 4" .

JMO.

Which is what I reckon re the gearing too - fine for mud. I'm usually in 3rd low in the mud.

Steve.

I'm a fence sitter in this. I have diff gearing and transfer case gearing.

I can drive stuff like this. (pic courtesty of Gwagensteve thanks)




I also have an auto...which helps with control. In this case my wheel speed needed to be inches per minute to maintain traction. Impossible with a manual box. it was a learning experience to have some guys spot me up this rock.

Dank: that doesn't make you a fence sitter, I don't think it's the fact that people don't like diff gears all together it's just that diff gears alone don't offer low enough gearing. You would have been more controlled driving that with 6.5s then with 5.12s. Joes zook goes well becaus. It's auto and dual cased.

Glad i am not Mexican, that rock doesn't look like anything i wouldn't drive my wifes Prado up.

steve can you work out my crawl for me please

3 sp auto
6.5
4.88

from reading whats wrote, if you have to $$$ to upgrade to 4.9 or just go 6.5 it sounds like a better option..
i guess run what you got for a bit and change if needed.
budget for a clutch and tgears

r0ck_m0nkey wrote:Glad i am not Mexican, that rock doesn't look like anything i wouldn't drive my wifes Prado up.

Rock's scare us mexicans...there aren't many around, when we find one...we get kinda of excited...

Transfer gearing is better bang for your buck by far. Actually i'm surprised that some people think that doing diff gearing is cheaper. By the time you find a pair of 5.12 R&Ps and get them fitted, you'd be looking at $300-500 minimum anyway, not much cheaper than a set of gears. Granted, if your' old ma is a mechanic and you picked up the diff gears off the side of the road then it might be something to consider.

When I was in bogfrogs situation a few years ago I already had 4.9:1 tranny gears and 31s. Sweeet setup. i went to 34s and decided that 4.57s in the diff's would spread the load and provide the reduction I needed to maintain good on road and better offroad performance.it was about the same price as buying 6.5s but I end up with a stronger more reliable drivetrain.

dank wrote: In this case my wheel speed needed to be inches per minute to maintain traction. Impossible with a manual box.

I beg to differ, with 6.5 tc gears and 31" pedes I can go slow enough to crawl steps gnarlier than that and even on "crap on rock" pedes.

The control is the beauty, I can even ride the brake with the motor idling and go even slower before it stalls if I need to. Rocks are what I like do drive and superlow gearing is where it's at on rocks.

Spike_Sierra wrote:I really think we need a comparison between the two in a head to head style situation as all we have here is two sides loving their current setup. We should try and organise this, would be great tech!

I sort of have one of each. Not a totally fair comparison, but I will explain:

My Sierra is 31" tyres and 4.9 TC gears (3.7 diffs). High range is not low enough, but low range is great, I love it. The car also has a 1.6EFI motor, and a really nice clutch which both make it more driveable. TC gears are great, and in this application have worked almost perfectly, 3.9 diff gears would make it spot on for highway use I reckon, but not going to happen right now. The crawl ratio is about 66:1.

My LJ.... once again 31" tyres, but LJ50 transfer case, and 4.5 diffs. My reduction is in the transfer, but it almost equally effects H and L, so its akin to diff gearing IMO. It has a 1L carb motor, and a OK (but not great) clutch. This car is too low on the road, and revs like fark! The offroad gearing is OK, and quite tolerable, though a nice clutch would help. I do have to ride the clutch somewhat more in this car over my Sierra, however because the gearing is adequate, I don't have to burn the clutch, and set fire to my flywheel . This is about a crawl ratio of 51:1.


Ok so my point, from my own experience anyway.
You can make a car drivable, with just diff gearing, I have no doubt of this at all. However, you will likely adversely lower your high range to achieve this. Despite this getting into my much lower geared Sierra, feels shitloads better, and is far less tiring to drive! As for any adverse effects, both cars kill standard transfer mounts, and suffer from axle wrap (Sierra in the rear, LJ in the front).
Also a point that my two vehicles present, is the importance of the engine and clutch on how good your gearing will feel. EFI and torque lowers your effective gearing, I notied this when I put the G16 in my Sierra, my crawl speed dropped significantly . The issue of lockers making gearing 'feel' higher has all ready been mentioned, as have the effect of autos.

If anyone wants a straight opinion from me, here it is: If I could actually buy transfer gears for an LJ transfer case it would have them!!!



11_evl, my names not Steve , but your crawl is about 76:1 (2.4x6.5x4.88)